The bounce is already showing up in the Rasmussen tracking poll:
Friday September 03, 2004–For the second straight day, the Rasmussen Reports Presidential Tracking Poll shows President George W. Bush with 49% of the vote and Senator John Kerry with 45%. The Rasmussen Reports Presidential Tracking Poll is updated daily by noon Eastern
Bush is enjoying a modest Convention bounce. Today marks the first time since March 19 that he has held a 4-point lead on consecutive days. The President’s Job Approval is at its highest level since April and voters now view him a bit more favorably than John Kerry. Data provided to Premium Members shows that in the key Battleground States, perceptions of the President improved each day of the Convention.
My prediction is a five-point bounce, to continue until the debates.
UPDATE: Time shows an eleven-point bounce.